The invention relates to a method to improve planarity of a planarized surface.
Different materials have different removal rates during chemical mechanical planarization. When a surface is planarized, and when that surface has two materials having different removal rates coexposed, one material tends to become dished or recessed relative to the other. In some cases, when two materials having unlike polishing properties are exposed together, one material may be damaged, resulting in surface roughness. In structures in which planarity is important, such dishing, recessing, or surface damage is disadvantageous.
There is an advantage, therefore, in a method to reduce or prevent dishing, recessing, or damage at such a surface.